1. Technical Field
The present teaching relates to surgical procedure assistance. More specifically, the present teaching is directed methods, systems, and programming for surgical instrument guidance and tracking.
2. Discussion of Technical Background
For biopsy of tumors and for minimally invasive treatment of cancers by, e.g. radiofrequency ablation, the placement of needles and ablation probes to the target is one of the steps of the procedures. The current state of the art is to use an imaging device to guide the placement step by step. First, the patient is scanned with a computed tomography (CT) or magnetic resonance imaging (MRI) device. Then one or more needle paths are planned on the acquired images by determining appropriate needle entrance points on the skin and target points for each needle. Then one or more needles are placed into the patient body by moving the needles step by step toward the targets. In each step, only a small movement of the needle is made. This is due to safety reasons and due to the lack of a guidance system. After each step of needle advancement, the patient is scanned again with the imaging devices to check whether the planned path is being followed. Adjustment of the needle orientation is then made if it is found that the actual needle path would not reach the target if the current needle orientation is kept. After the needle orientation is adjusted, the needle is advanced for another step. Then the imaging device is used again to check the needle orientation for another possible adjustment of the needle. This step is repeated until the needle tip reaches the target position.
The above-mentioned image-guided method makes sure that the needle can reach the desired location. However, it is a time-consuming procedure. For lesions located in difficult positions, such as lesions deep in the organ or close to critical organs, such as major vessel branch, heart, or lung lobe fissures, only a small step may be advanced toward the target lesion for a more careful check of the needle position for each needle pass. In such situations, more than the usual number of needle passes may be needed. Ten or more needle passes may be needed. This poses extra radiation dose to the patient if CT imaging device is used. To overcome those problems, image-guided needle tracking systems have been developed, e.g., in U.S. Patent Application Publication No. 2012/0029387, Guo-Qing Wei, Jian-Zhong Qian, Cheng-Chung Liang, Xiaolan Zeng, Li Fan, Feng Ma, “Methods and systems for real-time surgical procedure assistance using an electronic organ map”. In such a system, an electromagnetic sensor is attached to the needle. After appropriate calibration and registration, the needle position and orientation is displayed in real-time in the CT image space and overlaid onto the CT images. The aiming of the needle to the target and advancement of the needle may be monitored in real-time, and it may be immediately seen whether the needle is in the right direction and whether it may hit the target before the needle is advanced. This technology reduces the number of passes to reach a target. Instead of trial-and-error, such a system also gives physicians greater confidence in performing the procedure.
Even with real-time needle tracking, more than one needle passes may still be needed to reach the target, especially for lesions in critical locations. Due to possible lesion position shift caused by breathing or tissue damage from needle, re-adjustment of the needle position and orientation may still be needed. The images acquired for each needle adjustment are currently not utilized by the tracking system to further improve the accuracy of the guidance for the next step of needle advancement. It is then highly desirable to utilize the information in the new images to update the tracking system, so that a more accurate guidance may be performed.